Heavy metals (HMs) persist in the environment and enter the human body via various pathways. Once stored in adipose tissue, they can be transferred to breast milk, posing risks to infants. Moreover, maternal diet plays a key role in influencing HM levels in breast milk. The aim of this study was to measure the concentration of HMs, including lead (Pb), cadmium (Cd), mercury (Hg), and arsenic (As), in the breast milk of Korean mothers, assess their potential health risks, and identify maternal dietary factors influencing HM concentration in breast milk. Survey data on maternal–infant pairs and breast milk samples from 209 healthy lactating mothers were collected between January and March 2023. Trained nurses manually expressed the breast milk to prevent external contamination, and maternal dietary intake was systematically assessed using the 24 h recall method. The concentrations of Pb, Cd, Hg, and As were measured, and a risk assessment was conducted using the estimated daily intake hazard quotient. A multiple linear regression model was employed to evaluate the association between the HMs in breast milk and maternal dietary factors. Cd was detected in 99% of the breast milk samples, and high detection rates were observed for Hg (97%), As (89%), and Pb (79%). Arsenic was the largest contributor to the potential health risks of HM-contaminated breast milk. Positive associations were observed between Pb concentration and legume and seaweed consumption, Cd concentration and vegetable and seaweed consumption, Hg concentration and sugar intake, and As concentration and meat intake. This study highlights that maternal dietary intake is closely linked to HM concentrations in breast milk, and elevated As levels potentially pose health risks to infants. These findings underscore the importance of adopting a healthy diet to reduce HM exposure in breast milk and to promote safer breastfeeding practices.

This study investigated possible associations between dietary patterns and blood heavy metal levels in Korean adults, using data from the Korea National Health and Nutrition Examination Survey (2012–2016). To explore these associations, demographic, physical activity, anthropometric, biochemical, and dietary data, including a food frequency questionnaire, were analyzed. Foods were categorized into 19 groups, and principal component factor analysis identified three dietary patterns: Meat and processed food-enriched diet (MPD), vegetables and milk-enriched diet (VMD), and fermented and fish-enriched diet (FFD). Multivariate logistic regression was used to evaluate the association between dietary patterns and high levels of heavy metals in the blood. The results showed that a high MPD score had a positive association with high levels of blood Pb (OR = 1.470, 95% CI = 1.173–1.842) and Hg (OR = 1.559, 95% CI = 1.259–1.932); a high FFD score also showed a positive association with high levels of blood Pb (OR = 1.492, 95% CI = 1.227–1.814) and Cd (OR = 1.276, 95% CI = 1.045–1.559). In contrast, VMD score was negatively associated with high levels of blood Pb (OR = 0.760, 95% CI = 0.628–0.920) and Cd (OR = 0.948, 95% CI = 0.781–1.151). Moreover, the effect of each dietary pattern on blood heavy metal levels showed differences by sex. Some dietary patterns, such as a high intake of meat, processed foods, fermented foods, and fish, can increase blood heavy metal levels, whereas other dietary patterns, such as vegetables and milk, have a protective effect against heavy metal concentrations.